Magneto



June 5, 1923. A 17,457,463

i W. E. SCHWARZMANN MAGNET() FiledJan. ll. 1921 A TTORNE Y.

24 was Patented June 5, 1923.

UNITED STATES PATE-NT OFFICE.

k'WOLFGANG E. SCHWARZMANN, OF LONGMEADOW, MASSACHUSETTS, ASSIGNOR TO AMERICAN BOSCH MAGNETO CORPORATION, OF SPRINGFIELD, MASSACHUSETTS,

A CORPORATION OF NEW YORK.

MAGNETO.

Application led January 11, 1921. Serial No. 436,626.

T 0 all whomz' may concern:

Be it known that 1, lVoLrGANG E. SCHWARZMANN, a citizen of the United States, residing at 51 Bellclaire Avenue, Longmeadow, in the county of Hampden, State of lwlassachusetts, have invented certain new and useful Improvements in Magnetos; and I do hereby declare the following to be a full,-clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to magnetos having permanent magnets and parA ticularly to one of simple, compact and efficient construction and is an improvement on my co-pending application, Serial No. 278,176.

Heretofore, the side arms or limbs of the permanent magnet were made to contact with the rear face of the pole shoes throughout substantially the length of such face and particularly with that portion of such rear face extending from the end of the shoe nearest the U-bend or cross-bar of the magnet. The effective length or the magnetomotivc force of a side arm was thus regarded as substantially proportional to the length of the side arm extending back from such end of the shoe, and where it was desired to have a stronger magnet, the side arms had to be lengthened between such end of the pole shoe and the cross-bar. It is, therefore, an object of my invention to increase the magneto-motive force or the effective length of the side arms without actually tangibly lengthening or adding4 magnetic material to such bars. l accomplish such object, among others, 'as hereinafter more fully disclosed.

It is, therefore, a part of my invention to construct a magneto with a permanent magnet having side arms and a cross-bar there between, such arms and bar being preferably flat, and with pole shoes having raised portions, preferably of elongated form, or narrow and fla-t, and disposed transversely of the shoes, and also preferably located intermediate the ends of the shoes, the magneto also having a non-magnetic casing having portions interposed between the crossbar and the pole shoes with the raised portions ofthe pole shoes and the ends of the cross-bar projecting outwardly of the casing portions for contact with the magnet, suitable means, including fastening means passing through the raised portions of the pole shoes, being used to maintain the magnet arms in contact with the raised portions of the pole shoes and the ends of the crossbar.

As another part of the invention, whether or not the raised portions of the pole shoes be of elongated form, or narrow and flat, and transversely disposed with respect to such shoes, and whether or not the side arms and the cross-bar of the permanent magnet be flat, the pole shoes may be embedded in the casing of the magneto at the time of molding the casing so as to permanently fasten the shoes in place. lVhen the pole shoes are located in the mold at the time of casting the casing of the magneto, the shoes may move slightly out of proper place. When the casting is cooled and ready for attachment of the magnet arms and other parts. it is merely necessary to machine the raised portions of the shoes and, if necessary, the ends of the cross-bar. It is difficult to` machine the outer surfaces of the pole shoes at the corners without also injuring the material of the casing near such corners since such material may project slightly beyond the surface of the shoes. By the use of raised portions on the shoes this difficulty is avoided and the amount of machining is reduced to a minimum.

In the accompanying drawing illustrating a preferred embodiment of the invention:

Fig, 1 is a side view of the magneto; Fig. 2 is a vertical longitudinal section taken on line 9,-2 of Fig. 1; and Fig. 3 is a transverse section taken on line 3 3 of Fig. 1.

Referring more particularly to the drawing, the magneto comprises a casing of nonmagnetic material, preferably of aluminum, having top portion 1, a base plate poi tion Q and side portions 3, the latter being interposed between a cross-bar 4 of a perA manent magnet and pole shoe 5 on both sides of an armature 6 rotatably mounted in the magneto on a shaft 7 supported at one end in a bearing 8 suitably located in a recess formed in the cross-bar 4;, and at the other end in a bearing 9 suitably located in a recess in an end casing portion 10. A permanent magnet has flat side arms 11 which are secured to the pole shoes 5 and to the ends of the cross-bar 4 b y cap screws 12 and 13. Upon the exterior of the cross-bar 4 is mounted an interrupter housing 14 supported in an annular flange 15 formed on the bar 4 and containing an interruoter device 16, of usual form, connected to the shaft 7 to operate therewith, the outer end of the housing 14 being closed by a suitable end cap 17 held in position by a spring clip 18 of usual structure. lVithin the casing and supported upon the shaft is a collector 19 secured to the shaft 7 to rotate therewith, the collector having a conducting ring 20, with which engages, in the usual manner, a collector electrode mounted in the electrode post 21 connected to the side of the casing portion 10 and electrically connected to a lead Q2, which lead is connected at its other end to a distributor, (not shown). @n the opposite side of the armature, from that of the collector, is mounted a condenser 23 which may be connected across the contacts of the interrupter in the usual manner. The armature comprises a core Q4 of magnetic material, rotor shoes 25, and primary and secondary windings 26 and 27. The sha-ft 7 is tapered at the driving end thereof to receive a. suitable coupling from the shaft driven by the engine in a manner well understood.

In this type of magneto, it is advantageous to permanently attach the stator pole shoes 5 to the non-magnetic casing of the magneto at a time when the casing is cast in the mold, so that the pole shoes will be embedded in the molded casing and thus avoid the necessity of using fastening means as well as the machining of the parts for a proper litting together thereof. It has been found, however, that the pole shoes occasionally will become slightly moved out of place during the molding or casting operation and much machining of the outer surfaces of the pole shoes usually is necessary in order to get a proper flat contact of the side arms of the permanent magnet with such surfaces of the pole shoes. Machining of such surfaces, however, is diflicult particularly at the corners thereof since the corners may be embedded a little below the surfaces of the surrounding casing portions and, therefore, if the corners are to be machined so that the vside arms of the magnet may contact properly with the pole shoes, the surrounding portions of the casing will also be injured and disgured. I have also found, after machining has occurred and the magneto'installed, that repairs, such as the replacing of an end plate to the magneto, such as a cross-bar 4, requiresv machining' of the end plate, because such plate may be larger in dimension than the plate replaced, and, therefore, the rear end'of the side arms of the magnet will be more or less inclined to a position previously occupied and the contacting portions thereof with the outer surfaces of the pole shoes will not be perfectly fiat, and the magnetic flux between the side arms and the pole shoes will not be as perfect as it should be. I, therefore, construct the pole shoes of my invention with raised portions 28, preferably located intermediate the ends of the pole shoes or at least remote from the corners thereof, so that the machining of the surfaces of the raised portions will .not affect the non-magnetic casing portions of the magneto, and I also construct the crossbar 4 so that its ends will project outwardly beyond the casing portions 3 so that the side arms of the permanent magnet will rest only upon the outer surfaces of the raised portions of the shoes 15 and the ends of the cross-bar 4, the amount of machining necessary for this being reduced to a minimum. It will be observed that these raised portions may be located at any position between the ends of the pole shoes and, for convenience, I have constructed these raised portions of elongated form, narrow in width and extending transversely of the outer surfaces of the pole shoes, as is clearly shown by the dotted lines in Fig. 1 of the drawing.

In magnetos of the type herein described, the magneto-motive force of the pern'iaueut magnet having pole shoes depends upon the number ot magnetic elements present in the magnet bar or side arm between the pole shoes and the cross-bar of the magnet and it has thus been found that such magnetomotive force of such magnet is substaiuiially proportional to the length of the magnet side. arms extendingl back of the contacting portions of the pole shoes to the cross-bar of the magnet. This length termed the effective length l of the magnet, and, where it is desired to increase this effective length 7 of the magnet, it has been usual, heretofore, to increase the length of the side arms of the magnet so as to include a larger number of m netic elemeutsin the bar between the cross-bar and the ends of the pole shoes nearest such cross-ban But increas ing the length of the side hars for the purpose of obtaining greater magnetic effect destroys compactness by making the ir g neto larger and cumbersome, I have, there fore, discovered that, by making a simple change in the stator pole shoes, I can increase the effective length or magneto motive-force of the side arms of the magnet and still retain the same compact, simple form of magneto without in any way increasing the physical length ofthe side, arms' of the magnet. Accordingly, I provide the stator pole shoes with raised portions 28 of elongated form and narrover width, ei:- tenuing transversely of the outer surfaces of the pole shoes so as to contact with the side arms of the magnet at some distancev v net reluctance so that the magnetic lines of force are deflected to the pole slices at a greater distance from the cross-bar 4 than when the side arms contacted with the pole shoes from end to end thereof, and in this way, the effective length of the side arms is increased to the extent of the length of the side arms from the end 29 of the pole shoes to the nearest edge 30 of the raised portion 28.-

It will be observed that while I have shown the raised portion 28 substantially midway between the ends of the pole shoes 5, the greatest effective length of the side bars 1l would be obtained by locating the raised portion at or near the end 31 of the pole shoes'so that the greater portion of the rear surfaces ofthe pole shoes extending back tov the raised portion 28 would be spaced from the side arms 11. In this way a permanent magnet may be made to increase the magneto-motive force without in any way lengthening the magnet or increasing the size of the magneto.

Having thus described my invention what I claim is:

l. In a magneto, the combination ot a permanent magnet having sideI arms and a cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, raised portions ot said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in contact with said raised portions and the ends of said cross-bar.

2. In a magneto, the combination ot a per-v manent magnet having side arms and a cross-bar therebetween, pole -shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, raised portions intermediate the ends of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in Contact with said raised portions and the ends of said cross-bar.

3. In a magneto, the combination of a permanent magnet having side arms and a cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, raised portions of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in contact with said raised portions and the ends of said cross-bar, said pole shoes being permanently fastened to said casing.

4. In a magneto, the combination of a. permanent magnet having flat side arms and a flat cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, raised portions of said pole shoes and the ends of said crossbar projecting outwardly into Contact with said magnet arms, and means for maintaining said magnet arms in contactwith said raised portions and the ends of said crossbar.

5. In a magneto, the combination of a permanent magnet having ilat side arms and a flat cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, raised portions intermediate the ends of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in contact with said raised portions and the ends of said cross-bar.

6. In a magneto, the combination ot a permanent magnet having side arms anda cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, transversely disposed elongated raised portions of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in contact with said raised portions and the ends of `said cross-bar.

7. In a magneto, they combination. ot a permanent magnet having side arms and a cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said crossbar, transversely disposed elongated raised portions intermediate the ends of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means 'for main taining said magnet arms in contact with said raised portions and the ends oi said cross-bar.

8. In a magneto, the combination of a permanent magnet having flat side arms and a flat cross-bar therebetween, pole shoes for said magnet and a non-magnetic casing having portions interposed between said pole shoes and said cross-bar, transversely disposed narrow lat raised portions of said pole shoes and the ends of said cross-bar projecting outwardly into contact with said magnet arms, and means for maintaining said magnet arms in Contact with said raised portions and the ends of said crossbar.

9. In a magneto, the combination of a permanent magnet having flat side arms and a flat cross-bar therebetween, pole shoes for said magnet and a non-magnetic easing having portions interposed between said pole shoes and said cross-bar, transversely disposed narrow fiat raised portions intermediate the ends of said pole shoes and the ends of said Cross-bar prlojeeting outwardly into Contact with said magnet arms, and means for maintaining said magnet arms in Contact with said raised portions and the ends of said Cross-bar.

lO. In a magneto, the combination of a permanent magnet having side arms and a cross-bar detac-hably fastened therebetween, pole shoes for said magnet and a non-magnetio casing having portions interposed between said pole shoes and said Cross-bar, raised portions of said pole shoes and the ends of said cross-bar projecting outwardly into Contact with said magnet arms, and means passing through said raised portions for fastening said side arms in Contact with said raised portions.

ll. In a magneto, the combination oit a permanent magnet having side arms and a erossbar detaehably fastened therebetween, pole shoes for said magnet and a non-mag netio easing having portions interposed between. said pole shoes and said cross-bar, transversely disposed elongated raised portions of pole shoes and the ends oi: said cross-bar projecting outwardly into Contact with said magnet arms, and means passing` through said raised portions for fastening said side arms in Contact with said raised portions.

l2. In a magneto, the combination oiE a permanent magnet having side arms and a Cross-bar detaohably fastened therebetween,

pole shoes for said magnet and a non-niagneftio casing having portions interposed between said pole shoes and said eross-bar, transversely disposed elongated raised portions intermediate the ends of said pole shoes and the ends ot said cross-bar projecting outwardly into Contact with said magnet arms, and means passing through said raised portions for fastening said side arms in Contact with said raised portions.

13. In a magneto, the combina-tion of a permanent magnet having flat side arms and a flat erossba:r de-taehably fastened therebetween, pole shoes for said magnet, and a non-magnetie easing having portions inten posed between said pole shoes and crossbar, said pole shoes having transverse elongated lat raised portions on said pole shoes intermediate the ends thereof, said raised portions and the ends of said cross-bar projecting outwardly or said casing portions into Contact with said magnet, and 'tastening means passing through said raised portions for maintaining said side arms in contact with said raised portions.

14. In a magneto, the Combination of a permanent magnet having side arms and a detachable cross-bar therebetween, pole shoes for said magnet, a non-magnetic easing having portions interposed between said pole shoes and said cross-bar, raised portions of said pole shoes and the ends ot said Cross-bar projecting outwardly ot said easing portions into Contact with said magnet, and means for maintaining said side arms in Contact with said raised portions and the ends of said Cross-bar, said pole shoes being embedded in said Casing.

In testimony whereof I ailix my signature.

WOLFGANG E. SCHWARZMANN. 

